Review Question - QID 7738

Soft-tissue sarcomas found near joints are very rare. The MRI scan is clearly not benign fat (lipoma) but could be consistent with any sarcoma, myxoma, or ganglion cyst. The biopsy specimen, however, is not a cyst or myxoma (generally very acellular). This is a high-grade liposarcoma because it has high-grade cellular morphology and is not a biphasic picture. Furthermore, there are lipoblasts in the biopsy specimen. High-grade liposarcomas may have very little recognizable fat cells on the biopsy specimen. A biphasic synovial sarcoma has slit-like areas that look almost like glands and other more solid cellular areas. The name, synovial sarcoma, implies that it is found in the synovium, but that is not true. It is a misnomer concerning the pathologic appearance. A myxoma would have this MRI appearance but would be much less cellular on the biopsy specimen.